Electromagnetic relay



Feb. 6, 1951 R. L. BROWN ELECTROMAGNETIC RELAY Filed Oct. 15, 1947 3 Sheets-Sheet 1 26 J 2 IIZA ls INVENTOR BUBEBT LBHUlL/N BY ATTORNEY aim d Feb. 6,. 1951 2,540,185 ELECTRGMAGNETIC RELAY Robert L. Brown, Teaneck, N. L, assignor to Bendix Aviation Corporation, Teterboro, N. J., a

corporation of Delaware Application October 15, 1947, Serial No. 779,991

'2 Claims. 200-111) The present invention relates to relay switches and more particularly to a relay switch in which the several parts are arranged so as to permit quick and easy assembly and disassembly, ease of inspection and the spring .arranged so as to be insulated from the heat generated in the winding of the relay and at the relay contacts.

An object of the invention is to provide a relay switch having a pair of mounting bolts whereby the solenoid actuated plunger, the spring assembLv and the cover cap of the relay may be conveniently assembled and disassembled.

Another object of the invention is to provide a novel switch assembly including a pair of bolts upon which is slidably mounted a plastic heat insulating shield having amxed thereto a switch element resiliently supported through a novel leaf spring arrangement.

Another object of the invention is to provide a novel relay switch in which there is provided a leaf spring supported at opposite ends and having suspended therefrom the heat insulating 'shield, switch and relay plunger;

Another object of the invention is to provide a second leaf spring bearing at opposite ends upon the switch shield and permitting movement of the solenoid relative to the shield and switch upon the switch closing the relay switch to assure good contact between the switch elements.

Another object of the invention is to provide a simple fastening means for operatively connecting the leaf springs, switch mounting and solenoid.

Another object of the invention is to provide a novel relay having a flat type leaf spring suitably shaped and cooperating with supports arranged so as to cause the eflective length of the spring to decrease as it is deflected (pressure ap-.

plied) thus causing'its resisting force to increase at greater than a lincar rate so as to permit a greater final force to be applied to the contacts with no increase in size, supply power or effieiency of actuating solenoid and thereby utilize more of the available work of a given actuating solenoid by making the pressure versus deflection curve of the spring conform more closely to the Figure 2 is a sectional view of the relay switch of Figure 1 with the cover in place.

Figure 3 is a top plan view of the relay switch of Figure 1 with the cover removed and certain parts broken away to better illustrate the struc= ture thereof.

Figure 4 is a fragmentary sectional view of a modified form of the invention.

Referring to the drawings of Figures 1 and 2, numeral 10 indicates a cup shaped shell or casing member having a bottom closure plate Ii and positioned therein an electromagnet l2 connected by suitable conductors to terminals HA and I23. A pole piece i3 is screw threadedly mounted in the closure plate i I and projects into the electromagnet l2. The pole piece I3 cooperates with a plunger l4 formed of a magnetic material and Slidably mounted in the electromagnet I2. The plunger It has a channel A for opening the underside thereof to atmosphere.

The plung.r It has suitably fixed thereto a rod l5 which projects through a plastic non-electrical. conducting member l6. Mounted on the insulating member I6 is a heat insulating shield iii formed of a suitable non-electrical conducting plastic material.

Afllxed to the plastic shield I1 is an electrical switch bar l8 formed of a suitable conducting metal such as copper or silver and having mounted thereon switch contacts is and 20. The contacts l9 and 20 are arranged to cooperate with switch contacts 2! and 22 formed on conductor bars 23 and 24 respectively. The conductor bars 23 and 24 are mounted in a nonconducting electrical insulating plate as. The plate 25 is suitably fastened to the casing member ID by bolts 26 shown in Figure 1.

The rod l5, as shown in Figure 2, projects through leaf spring members 21 and 28 and is aflixed at its upper free end by a cotter pin 23 which, as shown in Figures 1 and 3, bears upon a plate 30 biased upwardly by leaf spring 28. Opposite ends of the leaf spring 28 are supported by members 3| and 32 formed of suitable nonelectrical conducting material. The supporting members 3I' and 32 fit over suitable pegs 33. The pegs 33 are screw threadedly engaged by bolts 34 which fasten the conductor bars 23 and 24 to the insulator plate 25, as shown in Figure 2.

It will be seen then that the leaf spring 23 assumes a dished shape and opposes downward movement of the plunger H. Between leaf spring 28 and leaf spring 21 there are provided washers 35 and a plate 36. The plate 38 bears upon the inverted dish shapzd leaf spring 21. End portions 31 of the leaf spring 21 bear upon the plastic heat insulator shield il. Recesses 28 are formed in the shield I! for receiving portions 38 of the leaf spring 21 to position the leaf spring 21 on the shield l1.

The leaf spring 21 resiliently opposss movement of the plunger is relative to the shield l1 and switch contactor 18. Thus upon downward movement of the plunger l4 under force of the electromagnet [2, the leaf spring 28 is first depressed and then upon contacts I9 and 20 engaging contacts 2i and 22 further downward movement of the plunger H further depresses leaf spring 28 and then depresses the leaf spring 21 so as to move the contacts i9 and 20 into intimate engagement with the contacts 2| and 22 respectively under force of the spring 21.

When the control switch of the electromagnet i2 is opened by the operator, the magnetic flux of the solenoid drops almost instantly to zero, and leaf springs 27 and 28 instantly and forcibly thrust the contact assembly l8 away from the terminal contacts 25 and 22 in spite of any burning together of the surfaces thereof which may have taken place, and so rapidly that any appreciable amount of arcing is prevented.

As shown in Figures 1 and 3 the heat shield I1 is slidably mounted one. pair of posts 40 having screw threaded portions ll engageable by nuts 42 which limit the upward movement of the shield it under force of spring 28. The screw threaded portions M are further arranged to project through suitable openings formed in a cover cap 53 as shown in Figure 2. The cover cap 43 protects the switch assembly and is secured in position by suitable fastening nuts M screw threadedly engaged on the portions 4 I.

It will be seen from the foregoing that the switch mechanism may be readily disassembled by removing the nuts 44 and cover cap 43, whereupon the spring assembly, heat shield l1, contacts i9 and 20, and solenoid l4 may be disassembled by the removal of the nuts 42. To further disassemble the leaf springs 21 and 2-8 and plunger H from the shield I'I it is necessary only to remove the cotter pin 29.

Moreover it will be noted that the leaf springs 21 and 28 are protected from the heat of the electromagnet l2 and the heat at contacts 19-21 and 20-22 by the novel plastic heat insulating shield I! which extends directly over and around the contact bar l8.

A modified form of the invention is illustrated at Figure 4 in which like numerals indicate corresponding parts to those shown in Figures 1-3.

In the modified form of the invention a plastic shield 58 is provided having projecting portions with an inclined surface 52.

A leaf spring 53 is provided in place of the spring 21 and the opposite ends of the leaf spring 53 rest on the inclined surface 52 of the portions 5!. An intermediate portion of the spring 53 acts through washers 35 so as to resiliently oppose downward movement of the plunger l4 relative to the shield 50.

As the plung.r l4 moves downwardly under force of the electromagnet l2, the force applied to the plunger M by the electromagnet i 2 continuously increases in excess of a linear. relation as the plunger I4 approaches the pole piece l3.

The point of contact of the leaf spring 53 with the inclined surface 52 moves downwardly along the surface 52 as the spring 53 is deflected downward. Thus the spring 53 cooperates with the inclined surfaces 52 of the portions 5| so-that upon the contacts l9-2l and -22 engaging,

further downward movement of the plunger ll causes the effective length of the leaf spring II to decrease as it is deflected (pressure applied). The latter action causes the resisting force of the leaf spring 53 to increase at greater than a linear rate so as to more nearly approximate the change in force of the electromagnet l2 and thereby provide a greater final contact closing force to be applied to the contacts i8-2l and 20-22 through spring 58 with no increase in size, supply power or efliciency of the actuating electromagnet l2.

The latter arrangement thus utilizes more of the available work of a given actuating solenoid by making the pressure versus deflection curve of the spring 53 more closely approximate the pull curve of the solenoid, although the force exerted on the contacts through the spring 28 will be sufliciently less than that of the electromagnet I! to assure the full extent of movement of the plunger l4 under varying operating conditions, as shown for example in Figure 4.

Although only two embodiments of the invention have been illustrated and described, various changes in the form and relative arrangements of the parts may be made to suit requirements.

What is claimed is:

l. A switch mechanism comprising an electromagnet, an armature operably positioned by the electromagnet, a heat insulating shield, switch elements mounted at one side of the shield, other switch elements cooperating with the first mentioned switch elements and carried by the electromagnet, a pair of posts on said armature of which at least one is of insulation for slidably mounting the shield on said electromagnet, a first leaf spring mounted at the other side of the shield, said first leaf spring supported at opposite ends by said shield, a releasable member connecting said first leaf spring to said armature and at a point intermediate the opposite ends of said first leafspring so as to resiliently connect said armature and shield, a second leaf spring mounted at said other side of the shield, and

. members carried by the electromagnet to support opposite ends of the second leaf spring, said releasable member connecting said second leaf spring to said armature at a point intermediate the opposite ends of said second leaf springto bias said armature and thereby said shield in an opposite direction from said electromagnet, and said shield tending to protect said first and second leaf springs from high temperatures at said switch elements and electromagnet.

2; A switch mechanism comprising an electromagnet, an armature operably positionedby the electromagnet, a heat insulating shield, switch elements mounted at one side of the shield, other switch elements cooperating with the first mentioned switch elements and carried by the electromagnet, a pair of posts on said armature of which at least one is of insulatiton for slidably mounting the shield on said electromagnet, portions projecting from said shield at the other side thereof and having inclined surfaces, a first leaf spring contacting said inclined surfaces at op- 1 posite ends thereof, a releasable member connecting said first leaf spring t said armature and at a point intermediate the opposite ends of said first leaf spring so as to resiliently connect said armature and shield, said first leaf spring 00- operating with said inclined surfaces so as to decrease the effective length thereof upon movement of said armature relative to said shield after closure of said second mentioned switch elements REFERENCES CITED by said first mentioned switch elements, a sec- The I no in f r f and leaf spring at said other side of the shield, me of g i 8 ences are 0 record in the and members carried by the electromagnet to support opposite ends of the second leaf spring, 5 UNITED STATES PATENTS I said releasable member connecting said second Number Name t leaf spring to said armature at a p int i r 705,082 Hewlett July 22, 1902 diate the opposite ends of said second leaf spring 978,377 Humphrey Dec. 13, 1910 to bias said armature and thereby Said S d in 2,110,171 Peters Mar. 8, 1938 an opposite direction from said electr m 10 2,381,075 Nelsen Aug. 7, 1945 and said shield tending to prevent said first and 2,391,277 Stapleton D 18, 1945 second leaf springs from being adversely affected 2,414,9 1 Mason t a1 Jan 23, 1947 by high temperature at said switch elements and electromagnet, FOREIGN PATENTS 1 Number Country Date ROBERT L. BROWN. 267,502 Great Britain Dec. 15, 1927 

